Additive manufacturing parts of optical systems is known in the art. US20150343673 A1, for instance, describes a method of manufacturing an optical-element, comprising (a) printing at least a part of a mold via additive manufacturing technology, (b) depositing a nanocomposite-ink at one or more voxels within the mold, (c) selectively curing the deposited nanocomposite-ink, and (d) repeating at least steps (b) through (d) until the mold is appropriately filled and cured. The mold is made from a plastic. In embodiments, the mold incorporates an optical insert. The optical insert is incorporated during the 3D-printing process. An example of the optical-element is a simple plano-convex lens with plano surface and convex surface.